The present invention relates to a high-fidelity loudspeaker arrangement, and more particularly to a loudspeaker arrangement having an acoustically-improved sound radiation or dispersion pattern, especially for high frequency signals.
In the prior art, multi- or omni-directional speaker arrangements are known. One such high-fidelity arrangement mounts four tweeters, i.e., a type of speaker responsive to the higher acoustic frequencies which is used for reproducing sounds of high pitch, about a vertical axis of an upright enclosure, and a single woofer, i.e., a type of speaker responsive to the lower acoustic frequencies, on the enclosure below the aforementioned grouping of four tweeters. Such an arrangement, however, achieves a sound distribution pattern only in the circumambient region of the enclosure which surrounds the vertical axis.
A significant problem in achieving a 360.degree. sound dispersion pattern is that of the frequencies of the sound signals to be reproduced. The higher the frequencies, the narrower will be the dispersion angle or width of the radiating sound waves. In order to improve the distribution of such high-frequency and low dispersion angle sound waves, hemispherically-shaped radiators having relatively large dispersion angles are utilized. However, the practical limitations of the design of the hemispherically-shaped radiators only give a maximum 180.degree. zone coverage up to frequencies of 4,000 Hz. At frequencies above 4,000 Hz, the size of the dispersion angle decreases.
Although the known high-fidelity arrangements have achieved a more or less uniform acoustical pattern for high-frequency signals without the occurrence of holes or regions of silence where the sound waves cancel out the effects of each other, the known prior art arrangements have not adequately eliminated such holes in planes other than the horizontal plane or in zones other than about the vertical axis of the loudspeaker enclosure. The quality of the sound reproduction is thus impaired for a listener.
The best acoustical sound pattern is one that creates a sound illusion that is free, open, and expansive. Such natural concert-hall sound realism is difficult to achieve with conventional loudspeaker arrangements. The sounds of the various musical instruments are not all specifically directed to a listener, but rather reach the listener through indirect means. For example, the sounds, and especially the high-frequency sounds, are directed upwardly to bounce off the walls and the ceiling of the concert hall so that the music fills the entire room. The conventional loudspeaker arrangements have attempted to design systems which can provide such sound realism; however, they are extremely costly and require a great deal of space.